intro to matlab (2) - university of waterloojzelek/teaching/syde252/matlab-tutorial2.pdf · intro...
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Intro to Matlab (2)syde252
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More on Matlab
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Matrix Comparison - watch
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Built logic functions for matrices
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Control flow - switch & case
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Control Loop - For Loop
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Short form for loops
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While loop - control flow
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Break - control flow
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MAtrix - array ops
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MAtrix ops
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Array ops
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M-files: scripts & functions
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Functions
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Scopes of variables
Matlab 2 - 13 pykc - Jan-8-10 E2.5 Signals & Systems – Matlab Tutorial 2
Functions
function r = myfunct (x) % Calculate the function: % r = x^3 - 2*x - 5 % x can be a vector
r = x.^3 - x.*2 -5;
Define function name and arguments Return variable
% on column 1 is a comment
» X = 0:0.05:3; » y = myfunct (x); » plot(x,y)
function myfunct.m
This is how plot on p.2-27 was obtained
Matlab 2 - 14 pykc - Jan-8-10 E2.5 Signals & Systems – Matlab Tutorial 2
Scopes of variables
! All variables used inside a function are local to that function ! Parameters are passed in and out of the function explicitly as
defined by the first line of the function ! You can use the keyword global to make a variable visible
everywhere ! As a good programming practice, only use global variables
when it is absolutely required
Matlab 2 - 15 pykc - Jan-8-10 E2.5 Signals & Systems – Matlab Tutorial 2
MATLAB Programming Style Guide (1)
! This Style Guideline is originally prepared by Mike Cook
" The first line of code in script m-files should be indicate the name of the file.
" The first line of function m-files has a mandatory structure. The first line of a function is a declaration line. It has the word function in it to identifies the file as a function, rather than a generic m-file. For example, for a function named abs_error.m, the the first line would be: function [X,Y] = abs_error(A,B)
" A block of comments should be placed at the top of the regular m
-files, and just after the function definition in function m-files. This is
the header comment block. The formats are different for m-files and functions.
Matlab 2 - 16 pykc - Jan-8-10 E2.5 Signals & Systems – Matlab Tutorial 2
Style Guide (2)
! Variables should have meaningful names. This will make your code easier to read, and will reduce the number of comments you will need. However here are some pitfalls about choosing variable names:
• Meaningful variable names are good, but when the variable name gets to 15 characters or more, it tends to obscure rather than improve code.
• The maximum length of a variable name is 19 characters and all variables must start with a character (not number).
• Be careful of naming a variable that will conflict with matlab's built-in functions, or reserved names: if, while, end, pi, sin, cos, etc.
• Avoid names that differ only in case, look similar, or differ only slightly from each other.
! Make good use of white space, both horizontally and vertically, it will improve the readability of your program greatly.
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MATLAB Programming Style Guide
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Style Guide (2)
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style guide (3)
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style guide (4)
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style guide (5)
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style guide (6) - a good example
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function of functions - fplot
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find zero
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find minimum
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integration of curve
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